\documentclass{exam-zh}

\examsetup{
  fillin = {
    % show-answer,
    no-answer-type = counter,
    no-answer-counter-index = 40
  },
  question = {
    index = 40,
    top-sep = -1ex,
    bottom-sep = -1ex,
  }
}

\begin{document}

An \fillin[apple] a day keeps the \fillin[doctor] away.

\begin{question}
  \begin{choices}
    \item apple
    \item banana
    \item egg
    \item water
  \end{choices}
\end{question}

\begin{question}
  \begin{choices}
    \item man
    \item woman
    \item doctor
    \item policeman
  \end{choices}
\end{question}

\begin{question}
  \begin{choices}
    \item man
    \item woman
    \item doctor
    \item policeman
  \end{choices}
\end{question}

\begin{question}
  \begin{choices}
    \item man
    \item woman
    \item doctor
    \item policeman
  \end{choices}
\end{question}


\end{document}